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This paper aims to explain the wideband operation of IEEE 802.11, illustrate the challenges for wider-bandwidth support, and propose solutions. First, we describe the wideband operation of conventional IEEE 802.11 systems and the low-efficiency problem related to their contiguous channel-bonding limitations. Next, we describe how the puncturing of...
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... 802.11 defines frequency channels for bandwidths of 20, 40, 80 and 160 MHz, as illustrated in Fig. 1. A basic service set (BSS) of IEEE 802.11 selects a primary 20 MHz channel where all the comprising stations (an access point station (AP) and its associated non-AP stations) of the BSS exchange basic control frames including beacon frames and perform a backoff procedure for channel access. The frequency channels of IEEE 802.11 are ...
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... real-time construction of a specific structure mode and (2) preconstruction of all or selected structure modes and real-time switching among them. Fig. 10 illustrates the opportunistic adaptation of the RU-info signaling structure for three bandwidth patterns in P80. In Case (a), the entire P80 is idle; thus, RU-info is organized into four content channels to minimize the signaling overhead. In Case (b), P40 is idle while S40 is busy, so RU-info is organized into two content channels, ...
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... we investigate how the throughput of a wider-bandwidth BSS is affected by a varying number of legacy single-channel (20 MHz) OBSSs. The wider-bandwidth AP is in a full-buffer state while each OBSS has a traffic rate of 50 Mbps. Legacy OBSSs are distributed randomly among 20 MHz channels. Each result point is an average of ten simulation runs. Fig. 11 shows the average of the transmission bandwidth and system throughput at MCS7. As the number of OBSSs increases, the transmission bandwidth gets more probable that a part of the RU-info channels are occupied by OBSSs. Thus, among the RU-info structure modes, the four-channel mode has the fastest decreasing rate while the one-channel ...
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... one-channel mode always achieves the highest transmission bandwidth. The two-channel mode is between them. The bandwidth utilization of the one-channel mode is the highest, however, its throughput is not always the best due to the signaling overhead and is even as low as the contiguous channel bonding for the number of OBSSs of zero as shown in Fig. 11(b) (the throughput of this mode is lower than that of the two-channel mode when the number of OBSSs is less than five). As a result, the trend of the throughput is similar to that of the transmission bandwidth but not exactly the same. The signaling overhead offsets the gain obtained from the extra utilization of frequency resources. If ...
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... is similar to that of the transmission bandwidth but not exactly the same. The signaling overhead offsets the gain obtained from the extra utilization of frequency resources. If the MCS of the payload increases (it is expected to increase further in future generations including EHT), the impact of the RU-info overhead increases (as shown in Figs. 12 and 13). As such, the best RU-info structure mode depends on the population of OBSSs in the operation bandwidth. In the meantime, the opportunistic adaptation adapts to the environmental conditions VOLUME 8, 2020 and switches between modes, thus always achieving the best bandwidth and throughput at the same time (e.g., as the number of OBSSs ...
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... evaluation of the statistical adaptation approach, the two versions of load-aware adaptation schemes-loadaware RU-info and load-aware bonding-are also considered for comparison in Fig. 11. In the simulation, these schemes estimate online the busy probability of each channel as the ratio of the CCA-busy occurrences of the channel among previous ten transmissions. The load-aware RU-info but the degree of degradation is somewhat limited. This implies that, if realtime RU-info construction is not affordable, the load-aware ...
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... 20 MHz operation bandwidths. Within each 80 MHz bandwidth, three OBSSs, one for each type, are deployed, with each P20 being randomly selected. The wider-bandwidth AP is in a full-buffer state while the traffic rate of OBSSs varies in [1,10,50] Mbps. The observed trend of the throughput performance with increasing traffic rate of OBSSs shown in Fig. 12 is similar to that with increasing number of OBSSs shown in Fig. 11. When the traffic rate is as small as 1 Mbps, the two-channel mode achieves higher throughput than the one-channel mode because of lower signaling overhead. As the traffic load increases, however, a mode with fewer channels is better for RU-info signaling success and ...
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... one for each type, are deployed, with each P20 being randomly selected. The wider-bandwidth AP is in a full-buffer state while the traffic rate of OBSSs varies in [1,10,50] Mbps. The observed trend of the throughput performance with increasing traffic rate of OBSSs shown in Fig. 12 is similar to that with increasing number of OBSSs shown in Fig. 11. When the traffic rate is as small as 1 Mbps, the two-channel mode achieves higher throughput than the one-channel mode because of lower signaling overhead. As the traffic load increases, however, a mode with fewer channels is better for RU-info signaling success and ultimately, for the traffic rate of 50 Mbps, the one-channel mode is ...
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... MCS results in the shorter airtime of the payload and the higher percentage of the RU-info airtime within a frame; the one-channel mode has the longest airtime of RU-info among all modes, thus having the highest percentage of the RU-info airtime. The throughput trends for all MCSs of IEEE 802.11ax with a varying number of OBSSs are shown in Fig. 13, also showing that as MCS gets higher the throughput gap ...
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... rates of 1, 5, and 50 Mbps. Since the traffic generation rates for stations are now heterogeneous, we evaluate the performance in terms of the traffic delivery ratio, which is obtained as the ratio of the achieved throughput to the generated traffic rate. The frequency of transmissions using different transmission bandwidths is shown in Fig. 14. When the OBSS's traffic generation rate is 1 Mbps, all schemes under comparison tend to use larger bandwidths overall. However, the onechannel mode has a significantly lower frequency of the usage of 320 MHz. This results from its low transmission efficiency due to the longest airtime of RU-info, which makes both the wider-bandwidth ...
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... throughput results are shown in Fig. 15 for varying OBSS loads. When the OBSS traffic generation rate is as low as 1 Mbps, the one and four-channel modes achieve the worst VOLUME 8, 2020 performance, implying that both the RU-info airtime and the signaling success probability are the affecting factors of the performance in this OBSS load condition. The two-channel mode ...
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... cumulative distribution functions (CDFs) of the per-station traffic delivery ratio are shown in Fig. 16 for the OBSS traffic generation rates of 1, 10, and 50 Mbps. The CDFs show that the opportunistic adaptation outperforms all of the fixed modes for all stations. This finding implies that the opportunistic adaptation achieves a performance gain by efficiently utilizing available bandwidth ...
Citations
... The frame format of PPDU for IEEE 802.11ax. 22 where the size for the acknowledgement frame in bytes is represented as ACK Size . Now, the duration necessary to send the VoWiFi packet successfully is specified by > ξ Ω in the following formula. ...
The rapid growth in wireless communication technology and the proliferation of multimedia applications, specifically Voice over Wireless Fidelity (VoWiFi), necessitate the exploration of innovative techniques for improving network performance and quality‐of‐service (QoS). This research paper presents an innovative approach to enhance VoWiFi cell capacity using aggregate medium access control protocol data unit (A‐MPDU) frame aggregation for variable bit rate (VBR) traffic. In this research article, we investigated the effect that the retransmission of voice packets has on the cell capacity of a wireless local area network (WLAN) standard that provides VoWiFi service while taking into account the A‐MPDU approach. When taking into consideration the constant bit rate (CBR) and VBR traffics, we compared the results obtained using WiFi 6 (i.e., IEEE 802.11ax) with older WLAN standards such as IEEE 802.11b/g/n/ac.
... For IEEE 802.11b standard, we have used the physical layer's time (i.e., T PHY ) as 96 s [18] and other layer's time (i.e., T MAC , T IP , T UDP , T RTP , T cRTP and T P ) by simply dividing the respective layer headers by 11 Mbps using (4). The PPDU frame format of IEEE 802.11b can be found in Fig. 128 can be found in Fig. 5(b) of [22]. The duration of slot is 20 s for IEEE 802.11b. ...
... So, it is necessary to find the maximum N MPDU that will be acceptable to the voice application. The maximum number of MPDUs to be aggregated in a single A-MPDU is found by solving the inequality given in (22) for the largest of N MPDU . In Fig. 8, we have shown the maximum number of MPDUs can be aggregated in a single A-MPDU for CBR traffic considering DIFS and AIFS for IEEE 802.11b/g/n/ac/ax/be. ...
The rising popularity of Voice over WiFi (VoWiFi) needs a dedicated effort to find new solutions to expand VoWiFi cell capacity. The main aim of this research is to enhance the VoWiFi cell capacity using aggregate MAC protocol data unit (A-MPDU) frame aggregation. In this regard, we developed a mathematical formula to estimate the number of VoWiFi users that can be allowed without compromising the quality-of-service (QoS) of existing VoWiFi calls over the Wireless Fidelity (WiFi) standards by considering Arbitration inter-frame spacing (AIFS), Compressed RTP (cRTP) and A-MPDU frame aggregation. In this work, we utilized AIFS to assess the channel state prior to transmit VoWiFi data from the sender user equipment (UE) to the receiver UE and Short Inter-frame Spacing (SIFS) to transmit Request To Send (RTS) / Clear To Send (CTS) and Acknowledgement (ACK) frames. Using our proposed model, we have examined VoWiFi cell capacity considering A-MPDU frame aggregation in constant bit rate (CBR) traffic using AIFS and DCF Inter-frame Spacing (DIFS) in IEEE 802.11b/g/n/ac/ax/be Wireless Local Area Network (WLAN) standards. Additionally, we have found the maximum number of MAC protocol data unit (MPDU)s aggregated in a single A-MPDU for IEEE 802.11b/g/n/ac/ax/be. Further, we have analyzed the effect of voice packet retransmission on the cell capacity of a WLAN standard that provides VoWiFi service considering A-MPDU technique.
... Additionally, a significant amount of work is currently being done to make Ultra Low Latency (ULL) application accessible via the subsequent version of Wi-Fi [7]. EHT is focused on attaining an extremely high rise in the peak of throughput, reaching at least 30 Gbps, which is three times higher or more than Wi-Fi 6, while concurrently minimizing the amount of latency experienced by users [8], [9], [10]. ...
... Wide channels promise a greater throughput. However, they present obstacles: flawless sync across sub-bands, primary channel obstructing access, power increase, and a higher peak-to-average power ratio resulting from more Orthogonal Frequency Division Multiplexing (OFDM) tones [9]. Modern APs feature dual/tri-band operation and extensive channel support. ...
The evolution of wireless communication has led to the introduction of IEEE 802.11be, a leading-edge wireless standard also referred to as Extremely High Throughput (EHT) or Wi-Fi 7. Multi-Link Operation (MLO) is the most innovative and disruptive technology proposed in this amendment, which holds the potential to revolutionize wireless networks. MLO aims to increase throughput through link aggregation, enhance reliability through redundant frame transmission over multiple links, and decrease latency by utilizing the earliest available link. However, to the best of our knowledge, there is no specific survey or review paper is dedicated solely to MLO, despite the extensive research conducted on Wi-Fi 7. Thus, this survey paper will bridge the gap by presenting an exhaustive overview of cutting-edge research spanning from 2010 to 2023, exclusively focused on MLO characteristics, current status and future directions. This study has discovered several open issues, including backoff count overflow, channel selection, load balancing and channel access fairness. These findings lay the groundwork for future research that has the potential to impact the current status of wireless communication significantly.
... The Sync with a primary link scheme (Sync-PL) is similar to the conventional wideband operation of IEEE 802.11 [4,5] In this scheme, an MLD runs a single BO in a primary link (PL) only and does not run in other links. When the primary link is about to reach a zero backoff count, the MLD performs a short clear channel assessment (CCA) for a point coordination function interframe space (PIFS) on each of the other links to check each's availability. ...
The next-generation wireless LAN standard named IEEE 802.11be supports a multilink operation to cost-efficiently boost throughput performance, for which an efficient multilink channel scheme is essential. The synchronous channel access scheme with an enhancement allowing multilink transmission before backoff completion greatly enhances the performance of multilink devices with no simultaneous transmit and receive capability, for which, however, backoff count compensation is necessary for coexistence with legacy and other multilink devices. In this paper, we identify the backoff count overflow problem of the enhanced synchronous channel access scheme with backoff compensation, which becomes aggravated once triggered due to repeated compensations. Then, we propose four solutions to mitigate this problem: limiting consecutive free-riding transmissions, limiting a compensated backoff value, using the contention window value of a main link, and balancing transmissions between links. Through comparative evaluation and analyses for dense single-spot and indoor random deployment scenarios, we demonstrate in terms of throughput and latency that the proposed solutions successfully mitigate the problem while preserving the coexistence performance.
... 59% of total mobile data traffic is expected to be delivered through Wi-Fi networks by 2022 [1]. For the continuing evolution of Wi-Fi networks [2], the next generation of IEEE 802.11 wireless local area network (WLAN) technology, named Extremely High Throughput (EHT), is under development by the 802.11be task group of IEEE (TGbe) [3,4], and is expected to be adopted by the Wi-Fi Alliance as Wi-Fi 7. EHT focuses on achieving an extreme increase in the peak throughput up to 30 Gbps, which is three times higher than that of Wi-Fi 6, while simultaneously reducing latency [5][6][7][8][9]. Mobile gaming and wireless virtual reality (VR) are two main use cases that are encouraging the development of EHT towards high peak throughput and low latency, whereas Wi-Fi 6 (also known as High Efficiency Wi-Fi or 802.11ax) was developed to ensure a stable user experience in dense deployment environments. ...
... • Sync-PL: This scheme resembles the conventional wideband operation of IEEE 802.11 [6,18], as illustrated in Figure 6. In this operation scheme, an MLD runs a single BO in a primary link (PL) only. ...
Multi-link operation is a new feature of IEEE 802.11be Extremely High Throughput (EHT) that enables the utilization of multiple links using individual frequency channels to transmit and receive between EHT devices. This paper aims to illustrate enhanced multi-link channel access schemes, identify the associated coexistence challenge, and propose solutions. First, we describe the multi-link operation of IEEE 802.11be and how the asynchronous and synchronous channel access schemes facilitate multi-link utilization. Next, we describe the design variants of the synchronous channel access scheme and demonstrate the associated coexistence challenge. Subsequently, we propose four features to address this challenge by assigning penalties to multi-link devices (repicking a backoff count, doubling the contention window size, switching to another contention window set, and compensating the backoff count) as well as five coexistence solutions derived from combinations of these features. Comparative simulation results are provided and analyzed for dense single-spot and indoor random deployment scenarios, demonstrating that the throughput and latency gains of multi-link operation differ between schemes. At the same time, we investigate the coexistence performance of multi-link operation with and without the capability of simultaneous transmission and reception and demonstrate that the proposed solutions mitigate the coexistence problem. In particular, compensating the backoff count achieves the highest coexistence performance among the proposed solutions, with a marginal throughput decrease of multi-link devices. A metric for evaluating both the throughput and latency gains and the coexistence performance of a multi-link channel access scheme using a single value is also proposed.
The rapid progress in wireless communication technology and proliferation of multimedia applications, including voice over WiFi (VoWiFi), demand exploration of innovative approaches to enhance the network performance and quality of service. We propose a technique for enhancing the cell capacity of wireless local area network (WLAN) access point that provides VoWiFi service in the sixth‐generation WLAN standard. The proposed technique uses the aggregate media access control protocol data unit (A‐MPDU) for frame aggregation with constant bit rate (CBR) traffic in the WiFi 6 standard (i.e., IEEE 802.11ax). On the other hand, the retransmission of voice packets substantially deteriorates the VoWiFi cell capacity. We compare the results obtained from the use of WiFi 6 with currently existing WLAN standards, such as IEEE 802.11b/g/n/ac. This comparison focuses on distributed coordination function interframe spacing (DIFS) and arbitration interframe spacing (AIFS) using CBR traffic. Using our technique, we can increase the VoWiFi cell capacity for CBR traffic by 24.25% and 25.20% when using DIFS and AIFS, respectively, while considering the A‐MPDU frame aggregation technique.
With the surge in demand for wireless traffic and network quality of service, wireless local area network (WLAN) has developed into one of the most important wireless networks affecting human life. In high density scenarios, large numbers of Access Point (APs) and Stations(STAs) will be deployed in a limited area, means large amount of signals will be overlapped and coverage between Basic Service Sets (BSSs), interference and collisions will become more severe, and if the sensitivity of edge STA detection channel is not enough, such as the energy detection (ED) threshold and reception sensitivity mismatch of STAs, edge STA’s throughput may slow down seriously. So in this paper, we propose an edge STA throughput enhancement method based on ED threshold and TXPower joint dynamic adjustment to solve the problem of edge STA deceleration caused by ED threshold and reception sensitivity mismatch. By appropriately adjusting the ED threshold and TXPower of the BSSs with deceleration edge STAs, improving the sensitivity of edge STAs detection channel, and opportunity of edge STA’s transmission packet is not greatly affected. Through the method of establishing mathematical model and simulation verification, it has great practical significance.KeywordsED thresholdTXPowerJoint dynamic adjustmentedEdge STAThroughput enhancement
